Prey behaviour

Clickbait title aside:

Random thought. Maturing quickly is a common evolutionary strategy for species that face high predation pressure, allowing them to reach sexual maturity and reproduce before they are eaten.

WoF dragons grow rapidly in their first few years. Slowing significantly once they reach the age of 4 (15 years old~ human eq.), and then again once they reach the age of 7 (young adult).

Other than "It's just fantasy/made up", what do you think could have caused it?

Could it have been outside factors, such as humans, megafauna, or were the early "feral" dragons a lot more prone to violence?

My "fun" theory suggests that dragons once dominated the world, only to be driven out by humans, leaving the dragons decimated and humans in a state of scientific decline for thousands of years. Come Scorching, it's the dragons ruling the world as the dominant species.
Only now are we seeing both dragons and humans interacting amicably in isolated incidents, which could, in the long run, spark cooperation and industrialisation. There would be a possibility that much further down the line, the spread of humans and everything that entails, would lead to demand for more space and resources. Driven by greed and apathy, both species could collide once more, repeating the cycle.
This could fit into the theme of the books, which is all about breaking cycles and choosing your own path despite destiny, regardless if manifactured or not.